In compounding rubber and rubber composition for use in pneumatic tires, it is common to utilize processing oils to soften and extend the rubber. Typically, aromatic processing oils, having a certain content of polycyclic aromatic (PCA) compounds or polyaromatic hydrocarbons (PAH), have been used. Recently, regulatory concerns have necessitated the use of processing oils having a lower PCA content.
Rubber formulations used in various tire components previously have been designed using conventional processing oils. However, in changing to the use of the lower PCA content oils, some loss in rubber compound performance is noted. It is, therefore, necessary to develop new rubber compounds that provide desirable performance levels while incorporating the use of low PCA oils.
U.S. Pat. No. 5,504,135 discloses a rubber processing oil and rubber products containing it, wherein properties rubber compositions containing less than 3 percent polynuclear aromatic compounds (PNA) were inferior to properties of compounds made using conventional oils.
U.S. Pat. No. 6,103,808 discloses a high aromatic oil and rubber composition and oil extended synthetic rubber using the same.
U.S. Published Patent Application No. 2001/0023307 discloses a rubber process oil and production process thereof.
U.S. Published Patent Application No. 2002/0045697 discloses rubber mixtures for producing highly reinforced vulcanizates with low damping behavior, wherein a low PCA oil is used in tires showing reduced rolling resistance and high wet skid resistance. The rubber mixtures disclosed therein also contain at least one glyceride and/or a factice.
U.S. Published Patent Application No. 2002/0000280 discloses a rubber composition comprising a low PCA oil and at least one glyceride.
U.S. Pat. No. 6,399,697 discloses a process oil and rubber composition using the oil.